In recent years, more and more wireless communication modules to be stored inside electronic apparatuses or wireless communication apparatuses such as cellular phones and the like have adopted a configuration in which plural antennas are formed on a single wireless communication apparatus. Particularly, in small size wireless communication apparatuses, a footprint of antenna portion in the wireless communication apparatus is reduced in order to downsize a built-in wireless communication system. Thus, it becomes more common to adopt the configuration in which plural antennas are mounted on a single printed board together with a wireless communication module.
Japanese Unexamined Patent Application Publication No. 2006-74446 describes a multiband antenna device in which two chip antennas are mounted on a printed board. FIG. 17(A) is a plan view of the antenna device described in Japanese Unexamined Patent Application Publication No. 2006-74446, and FIG. 17(B) is its bottom view. Two chip antennas 106 and 107 are mounted on a top surface of a printed board 102 inside mounting areas 108 and 109 that do not overlap a ground conductor portion 104. The ground conductor portion 104 includes a second ground conductor portion 104b that is extended by a predetermined length from a first ground conductor portion 104a in a direction toward an end portion, and a third ground conductor portion 104c and a fourth ground conductor portion 104d that are extended from the second ground conductor portion 104b in directions toward sides where the chip antennas 106 and 107 are located.